Farmall Cub Forum -- Questions and answers to all of your Cub related issues.
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I have owned my cub for a couple of years and it has been very easy to start. It began to have starting problems about a week ago. I replaced the carb and it continued to be difficult to start. I am now unable to start it. I have sprayed starting fluid into the air intake of the carb, then dropped the carb and squirted fluid into the manifold. Neither approach was successful. We get a blue spark at the mag but it is yellowish-white at the spark plugs. Should I start with new plug wires and spark plugs? If so, what plug should I purchase. I believe that I have seen D-21 recommend several times. What brand is this plug. Your suggestions will be appreciated. Dan
Harold: I do appreciate your offer but this is the cub at my son's house. Would you talk to your wife about moving to Waldo so you can be nearby when I have tractor problems? It would be a long commute to her school but I am sure she would see the value (to me) of having you near when tractor problems occur. In a serious tone, I do hope that she is recovering nicely. I have thought of you and your family several times this week. We will be visiting in Monroe soon, maybe the latter part of this week. Thanks again for your offer. Dan
Dan, the D-21 plug is a Champion, a fairly hot plug, which is fine if you don't work your tractor very hard (parade tractor) or if you have some oil fouling issues. The factory recomended plug is ,I believe, a D-16.
I'd try the plugs first, and check out the response from there.
V.P. of T.S.A. (taking stuff apart)
I installed a new set of plug and mag wires. Also new sparkplugs (D-21). The old plugs were in really bad shape. Discarded old gas, put in new. Tried starting (with and without choke). It didn't hit a lick. Tried starting fluid in the air inlet of carb, no results, so I dropped the carb and sprayed fluid directly into manifold. No results. Bypassed on off switch but still no indication that it would fire. I gave up for today. Again, I welcome your suggestions. I will try again later. Dan
Dan, if the spark is blue at the mag coil wire and yellow at the plug, you are losing energy through the cap. I would consider replacing the cap and rotor and re-checking the timing.
If you can't fix it with a hammer, you've got an electrical problem.
My wife says I don't listen to her. - - - - - - - - Or something like that!
Bigdog: I will try that next and will let you know the results. It was a good running Cub before this problem and I am sure that it will run good again. Not getting good results immediately is frustrating but, as I don't have any mechanical skills, I do feel that I am learning some do's and don'ts when working with Cubs. Thanks for your suggestions. Dan
When you are spraying starting fluid up the manifold, do you see any of the residue come out the exhaust? Any suction from the intake?
Harold: I haven't noticed any emissions from the exhaust. I spent time yesterday attempting to get to the points with no success. Two screws must be removed to pull a cover plate aside to access the points. There is so little working space between the oil filter housing and the screws and I can't get a screwdriver in to loosen the inside member of the two screws. We are coming to Monroe today and plan to return to Waldo on Monday. I will probably use some PB Blaster today and hope that it has lubricated the threads of the screws by Monday. You may remember seeing a tractor and implements in our shed which I bought for a brother-in-law a couple of years ago. He has given up on finding time to come down to pick it up so I bought them when we were in Missouri this past week-end. I believe that it is a 51 or 52 model. Dan
Sure hate to see a Missouri cub going to the mosquito state.
By your description of the 2 screws, I assume you have a magneto. It's usually easier to remove them to change the points and then retime then than to do it with the mag mounted. After you remove the rotor, it also will have to be timed. There is a good article on Rudi's server on working on the mags. There is a good possibility your mag coil is failing. They are a little pricey if you're not sure, but it's easy to temporarily (or permanently) replace them with a battery ignition coil.
Also are you hearing the snap of the mag impulse if you crank it by hand?
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Thanks, John. I had begun to believe that the mag might have to come off. That was to be my last option as I dreaded having to retime the unit. I guess if I am to own cubs that I need to learn how to time them. I have copied and kept many articles on timing the mag and these can supplement Rudi's article. I am sure I will be back with questions next week. Thanks to all. By the way John, you are certainly correct on the mosquitos. Like much of the south, we have received record amounts of rainfall in June and mosquitos are now a real problem. Dan
You can remove and replace a magneto without having to go through the full timing from scratch. It's pretty easy:
1) Before removing anything, crank the engine over by hand until you hear the impulse click.
2) Remove the distributor cap and note the direction the rotor is pointing.
3) Optional, put a small scribe mark from the magneto housing to the block. (A good layer of undisturbed dirt or sometimes a gasket will do as well.)
4) Remove the magneto and do whatever work is required.
5) Rotate the magneto until the rotor points the same direction as noted in step 2.
6) Bolt it back on and rotate to align the scribe marks, dirt deposit or . . .
7) Recheck the timing, which you will find back where it was before you started.
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